The Government has now completed its review of the Fast Reactor (initial capitals in the original). The Fast Reactor is of major strategic significance for the U. K.’s and the world’s future energy supplies. It… can create out of the spent fuel and depleted uranium which has so far arisen from our thermal programme fuel equivalent to our economically recoverable coal reserves.

The UK is among the world’s leaders in the development of this technology. Through the successful programme of research and development undertaken by the Atomic Energy Authority, which centers on the operation of the Prototype Fast Reactor and associated fuel cycle at Dounreay, we have demonstrated the feasibility and potential of this technology … The Government has therefore decided to continue with a substantial development programme for the fast reactor based on Dounreay…

In the wake of the demise of the Clinch River Reactor project, ANL scientists developed and promoted the Integral Fast Reactor (IFR) concept. Patterned after the EBR-II with its Integral Fast Reactor fuel cycle facility (see EBR-II discussion), the IFR would integrate the plutonium-breeder reactor with an on-site spent fuel pyroprocessing and electro-refining process. In this process, plutonium and the minor transuranic elements would be separated and recycled together into new fuel.

The IFR was advanced as the key to making the breeder reactor economical, proliferation-resistant and environmentally acceptable.73 There were ample grounds for skepticism, however. Most importantly, pyroprocessing looked still more expensive than conventional reprocessing. Moreover, were the IFR technology to be adopted by a non-weapon state it would provide the country with access to tons of plutonium in each co-located reactor and reprocessing facility. A cadre of experts trained in transuranic chemistry and plutonium metallurgy could separate out the plutonium from the other transuranic elements using hot cells and other facilities on-site. A 1992 study commissioned jointly by the U. S. Departments of Energy and State describes a variety of ways to use a pyroprocessing plant to produce relatively pure plutonium.74

Despite these problems, ANL was able to attract federal support for the IFR concept for a decade until the Clinton Administration cancelled the IFR program and the Congress terminated its funding in 1994. As a political compromise with Congress, it was agreed that while EBR-II would be shut down, funding of the fuel reprocessing research would continue—renaming it the "actinide recycling project."75 A decade later this program would be re-characterized and promoted as necessary for long-term management of nuclear waste—becoming the centerpiece of the George W. Bush Administration’s GNEP.

After Congress terminated funding for the IFR program, the DOE kept its pyroprocessing program alive by selecting it to process 3.35 metric tons of sodium-bonded EBR-II and FFTF spent fuel at INL. In 2006, the DOE estimated that pyroprocessing could treat the remaining 2.65 tons of this fuel in eight years at a cost of $234 million, including waste processing and disposal for a reprocessing cost of approximately $88,000/kg.76

From the very beginning, leaders of the fast-neutron reactor development program had safety concerns. Reactivity safety was studied theoretically using a number of criticality experiments under different scenarios such as refueling, transition from subcritical to supercritical, and the effectiveness and safety of the control rods. These findings were subsequently supported by practical experience with the BOR-60, BN-350 and BN-600. Additionally, special experiments were performed to study fires resulting from sodium leaks into the air (which can be effectively suppressed) and into the water in steam generators.

A more significant problem centered on the construction of the steam generator. Two types of steam generators were tested, water in pipe surrounded by sodium (straight-type) and sodium in pipe surrounded by water (reverse-type). Experience acquired from both types revealed that the reverse-type is safer and led to the idea of including an intermediate sodium heat-transfer loop between the radioactive sodium primary coolant and the steam generator.

…we now believe that the series ordering phase will begin in the earlier part of the next century… the development programme will be geared to this timescale… The Government and the Atomic Energy Authority have been having exploratory discussions with other countries to establish… the potential for collaborating with other countries as a means of securing the maximum benefits from this vital development programme.

Not everyone was convinced. Even Nuclear Engineering International had doubts. In February 1983, it declared:

The large amounts of money being spent worldwide by the nuclear industry on the development of fast breeder reactors is becoming increasingly difficult to justify… Will it ever be possible to recoup the vast sums that have been spent and the much greater sums that will need to be spent before the fast reactor can become a commercial option for electricity utilities? … Uranium will not be suddenly exhausted or become excessively expensive… There will be plenty of time to identify the trend… But perhaps of greater significance to fast reactor economics than the availability of uranium is the fact that with advances in techniques for the storage of irradiated fuel from light-water reactors utilities can avoid reprocessing. The uncertain and growing costs of reprocessing are then properly loaded on the fast reactor… In these circumstances fast reactors may never be economic… Evangelical fervour is not a substitute for sound technical argument.

In February 1984 the Comptroller and Auditor General published a terse report entitled "Development of Nuclear Power," expressing unease about the AEA’s financial performance; and the House of Commons Committee of Public Accounts looked into the matter. The committee chairman asked AEA chairman Sir Peter Hirsch "the estimated total cost of development" of the fast breeder. Sir Peter replied: "We have spent so far about £2400 million in 1982-83 prices. The forward development programme, assuming a certain profit for it, again in 1982-83 prices, is estimated to be £1300 million, the total being £3700 million." Asked "What have you got for all this money?" Hirsch continued:

The main thing we have got is that we have got the expertise in the UK to go forward to build a CDFR and then have a commercial programme.

For that money we shall be, we are, in the position to give the UK the option of having a fast reactor capability for producing electricity. We have done a cost benefit analysis of what the country would get out of it, making certain assumptions. Assuming that commercialization of the fast reactor starts in about 2015 and you have a programme of building fast reactors of 1.25 gigawatts electrical for about 30 years, you can estimate, admittedly on making certain assumptions of uranium price escalation, that you would expect benefits of several billions of pounds compared to the cost you would have to pay if you got the electricity from PWRs…

On 19 July 1984, the Select Committee on Energy pointed out the real import of Hirsch’s evidence:

Since 1955-56 some £2400m (in 1982-83 money values) has been voted for fast reactor R&D, and in the twenty years since 1962-63 real expenditure has remained remarkably steady at between £85m and £120m a year. In evidence to the Committee of Public Accounts on 2 April 1984, the Chairman of the UKAEA estimated that a further 25-30 years and additional R&D expenditure of £1300m (in 1982-83 prices) will be needed to reach the stage ‘where one hopes to obtain a commercial station’. To this figure must be added £2 billion construction costs for a commercial demonstration reactor and £300 million for reprocessing facilities, giving total estimated further expenditure of £3.3 billion and a cumulative figure of £5.7 billion. This implies that at present the fast reactor is roughly halfway through a perceived 60-year research, development and demonstration programme…

R&D expenditures on advanced nuclear power reactors today are far less than in the 1970s (see figure 1.1, Overview, chapter 1). This has led to more international collaboration.

One such collaboration between government-funded nuclear R&D establishments is the Generation IV International Forum (Gen IV Forum). This forum was launched in 2001 at the instigation of the United States to facilitate international collaboration on the design of a new generation of nuclear reactors to be deployed after 2030. In 2002, the Forum selected six types for study, including three fast-neutron breeder reactors cooled respectively by liquid sodium, a liquid lead-bismuth alloy, and helium. Thus far, the collaborations on these efforts have focused on coordinating and pooling national research on reactor design, safety, proliferation resistance, fuel fabrication technologies, material development, and other topics.77

A second international collaboration, the International Project on Innovative Nuclear Reactors and Fuel Cycles (INPRO) was initiated by a resolution of the International Atomic Energy Agency (IAEA) Board in 2001. In part because of the exclusion from the Gen IV Forum of Russia and other states with which the United States did not have agreements for nuclear cooperation. Thus far, INPRO has produced a report on "Guidance for the Evaluation of Innovative Nuclear Reactors and Fuel Cycles" and manuals on how to implement the assessment of "innovative nuclear-energy systems." Currently, INPRO members are collaborating on research projects and researchers from different countries are assessing proposed systems.78

In 2006, the George W. Bush Administration proposed GNEP with a goal of expanding nuclear power in the United States and abroad while reducing both the nuclear weapon proliferation risks and the requirements for long-term geological disposal of radioactive waste. To achieve these goals the Administration proposed abandoning the once-through nuclear fuel, where nuclear fuel would be permanently sequestered in geologic repositories, in favor of the development and deployment of a closed fuel cycle based on advanced nuclear fuel reprocessing and fast-neutron "burner" reactors.

The GNEP program envisioned using fast-neutron reactors to burn rather than breed plutonium and the minor transuranic elements (neptunium, americium, and curium) to avoid having to place these long half-life radioactive materials into a geologic waste repository. The ratio of the number of fast reactors to conventional reactors depends upon the conversion ratio, defined as the ratio of the rate of production to the rate of destruction of the transuranic isotopes in the fast-neutron reactor. For fast-neutron reactors a wide range of conversion ratios is possible depending upon the reactor design. The lower the fast reactor conversion ratio, the fewer burner reactors would be required, with the number of fast burners proportional to 1/(1 — CR). In 1996, a National Research Council report cited General Electric as believing that the lowest possible conversion ratio that could be obtained using its PRISM fast reactor design, consistent with acceptable safety, as 0.6.79 ANL more recently claims that a conversion ratio of 0.25 can be safely achieved.80 Assuming the fast reactor conversion ratio is in the range of 0.25 to 0.6, 40-75 GWe of fast-reactor capacity would be required for every 100 GWe of light-water reactors.81

Despite the shift of mission from plutonium breeding to burning, the dream of breeding lives on. Although one ANL design of a fast-neutron burner reactor features a compact core where the inert (steel) blanket could not be readily converted to a blanket with uranium or depleted uranium, suitable for breeding, ANL in 2007 favored another design that could be converted to a breeder more easily but would cost more — on the order of 0.8 cents per kilowatt-hour.82

Conclusion

Although there are safety issues generic to liquid metal fast reactors, it does not appear that they were the predominant reasons for the demise of the breeder program in the United States. More important were proliferation concerns and a growing conviction that breeder reactors would not be needed or economically competitive with light-water reactors for decades, if ever.

Under GNEP, the DOE expressed renewed interest in fast reactors, initially as burner reactors to fission the actinides in the spent fuel of the light-water reactors. So far, the new designs are mostly paper studies, and the prospect of a strong effort to develop the burner reactors is at best uncertain. The Obama Administration has terminated the GNEP Programmatic Environmental Impact Statement and efforts by DOE to move to near-term commercialization of fast reactors and the closed fuel cycle for transmutation of waste. As this report went to press, it was debating whether to even continue R&D on fast-neutron reactors.83 The economic and nonproliferation arguments against such reactors remain strong.

Contributors

Thomas B. Cochran is a senior scientist in the nuclear program and holds the Wade Greene Chair for Nuclear Policy at the Natural Resources Defense Council (NRDC). He served as director of the nuclear program until 2007. He is a member of the Department of Energy’s Nuclear Energy Advisory Committee. Cochran is the author of The Liquid Metal Fast Breeder Reactor: An Environmental and Economic Critique (Washington, D. C.: Resources for the Future, 1974). Cochran received his Ph. D. in physics from Vanderbilt University in 1967. He was a co-author of chapter 7, Fast Reactor Development in the United States.

Harold Feiveson is a Senior Research Scientist and Lecturer in Princeton University’s Woodrow Wilson School. He has a PhD in public affairs from Princeton University (1972). Feiveson is the editor of Science & Global Security. Along with Professor von Hippel, he was the co-founder and co-director of the Program on Science and Global Security until July 2006. Feiveson was a co-author of Chapter 7, Fast Reactor Development in the United States.

Walt Patterson is Associate Fellow in the Energy, Environment and Development Programme at Chatham House in London, UK, and a Visiting Fellow at the University of Sussex. A postgraduate nuclear physicist, he has been actively involved in energy and environmental issues since the late 1960s. Keeping The Lights On: Towards Sustainable Electricity (Chatham House/Earthscan 2007, paperback 2009) is his thirteenth book. He has also published hundreds of papers, articles and reviews, on topics including nuclear power, coal technology, renewable energy systems, energy policy and electricity. He has been specialist advisor to two Select Committees of the House of Commons, an expert witness at many official hearings, a frequent broadcaster and advisor to media, and speaker or chair in conferences around the world. He has been awarded the Melchett Medal of the Energy Institute. The Scientific American 50 named him ‘energy policy leader’ for his advocacy of decentralized electricity. His current project for Chatham House and the Sussex Energy Group is called "Managing Energy: for climate and security". Patterson was the author of chapter 6, Fast Breeder Reactors in the United Kingdom.

Gennadi Pshakin is head of the Analytical Center for Nonproliferation at the Institute for Physics and Power Engineering (IPPE), Obninsk, and teaches at Obninsk Nuclear Technology University. Between 1985 and 1993, he worked as an IAEA safeguards inspector, and in 2003 was part of the IAEA team in Iraq. In the 1990s, he participated in negotiations on the trilateral initiative (USA — Russia — IAEA). Since 2001 he has been part of the INPRO project on developing a Proliferation Resistance Assessment Methodology and his recent research covers material protection, control, and accounting activities in Russia. His PhD (1980) was in nuclear engineering. Pshakin was the author of Chapter 5, The USSR — Russian Fast Neutron Reactor Program

M. V. Ramana is currently a Visiting Scholar with the Program in Science, Technology and Environmental Policy and the Program on Science and Global Security at the Woodrow Wilson School of Public and International Affairs, Princeton University. He has a PhD in physics (1994) and has held research positions at the University of Toronto, Massachusetts Institute of Technology, and Princeton University. He has taught at Boston University, Princeton University, and Yale University. His research focuses on India’s nuclear energy and weapon programs. Currently, he is examining the economic viability and environmental impacts of the Indian nuclear power program. He is actively involved in the peace and anti-nuclear movements, and is associated with the Coalition for Nuclear Disarmament and Peace as well as Abolition-2000, a global network to abolish nuclear weapons. Ramana was the author of Chapter 3, India and Fast Breeder Reactors.

Mycle Schneider is an independent nuclear and energy consultant. He founded the Energy Information Agency WISE-Paris in 1983 and directed it until 2003. Since 1997 he has provided information and consulting services to the Belgian Energy Minister, the French and German Environment Ministries, the International Atomic Energy Agency, Greenpeace, the International Physicians for the Prevention of Nuclear War, the Worldwide Fund for Nature, the European Commission, the European Parliament’s Scientific and Technological Option Assessment Panel and its General Directorate for Research, the Oxford Research Group, the French National Scientific Research Council, and the French Institute for Radiation Protection and Nuclear Safety. Since 2004 he has been in charge of the Environment and Energy Strategies lecture series for the International MSc in Project Management for Environmental and Energy Engineering Program at the French Ecole des Mines in Nantes. In 1997, along with Japan’s Jinzaburo Takagi, he received Sweden’s Right Livelihood Award "for serving to alert the world to the unparalleled dangers of plutonium to human life." Schneider was the author of chapter 2, Fast Breeder Reactors in France.

Tatsujiro Suzuki is an Associate Vice President of the Central Research Institute of Electric Power Industry, as well as a Senior Research Fellow at the Institute of Energy Economics of Japan. He is also a Visiting Professor at the Graduate School of Public Policy, University of Tokyo. He has a PhD in nuclear engineering from Tokyo University (1988). He was Associate Director of MIT’s International Program on Enhanced Nuclear Power Safety from 1988-1993 and a Research Associate at MIT’s Center for International Studies (1993-95) where he co-authored a report on Japan’s plutonium program. For the past 20 years, he has been deeply involved in providing technical and policy assessments of the international implications of Japan’s plutonium fuel-cycle policies and in examining the feasibility of interim spent-fuel storage as an alternative. He is a member of the Advisory Group on International Affairs of the Japan Atomic Energy Commission and now is also a member of the Ministry of Economy, Trade and Industry’s Advisory Committee on Energy. Suzuki was the author of chapter 4, Japan’s Plutonium Breeder Reactor and its Fuel Cycle.

Frank von Hippel is Professor of Public and International Affairs at Princeton University’s Woodrow Wilson of Public and International Affairs. He has a PhD in nuclear physics (1962) from Oxford University. He is a co-founder of Princeton’s Program on Science and Global Security. In the 1980s, as chairman of the Federation of American Scientists, he partnered with Evgenyi Velikhov in advising Mikhail Gorbachev on the technical basis for steps to end the nuclear arms race. In 1994-95, he served as Assistant Director for National Security in the White House Office of Science and Technology Policy. He has worked on fissile material policy issues for the past 30 years, including contributing to: ending the U. S. program to foster the commercialization of plutonium breeder reactors; convincing the United States and the Soviet Union to embrace the idea of a Fissile Material Production Cutoff Treaty; launching the U. S.-Russian cooperative nuclear materials protection, control and accounting program; and broadening efforts to eliminate the use of HEU in civilian reactors worldwide. Von Hippel was the author of chapter 1, Overview: The Rise and Fall of Plutonium Breeder Reactors and a co-author of chapter 7, Fast Reactor Development in the United States

Because of the added secondary circuit, the total amount of structural material in the BN-600 is approximately 50 percent more than for the VVER-1000 (1000 MWe) light-water reactor.16 The estimated cost of BN-800 construction is $2.2-2.5 billion, approximately 11 percent greater than that of the standard VVER-1000 or costing approximately 40 percent more per kilowatt (KW).17 This higher capital cost and the higher cost of plutonium fuel relative to low-enriched-uranium fuel would make electricity from the BN-800 much more expensive than that from the VVER-1000.

Scientific problems addressed, solved and remaining

Most of the technical problems relating to fast-neutron reactors were solved through extensive experimental and theoretical studies performed during the first 40 years of the program. Various reaction cross sections were measured for neutron calculations (criticality, neutron flow distribution, reactivity effects, control-rod effectiveness, etc.). The results were replicated in a number of criticality experiments. The criticality of the BN-350 was predicted within 1 percent (198 fuel assemblies calculated versus 200 experimental). Control-rod effectiveness was estimated with less than 10 percent uncertainty and temperature and power reactivity coefficients with 15-20 percent uncertainty. The startup measurements on the BN-600 produced similar results. There has been significant progress towards the understanding of the swelling effects in steel from high neutron fluence (>1022 n/cm2).18 The behavior of liquid metals, particularly liquid sodium, was studied at a number of IPPE’s experimental facilities over 50 years. Practically all aspects were studied and the results explained theoretically. New requirements for nuclear safety promulgated after the Chernobyl accident will require additional study but will likely not raise new scientific obstacles.

Public concern about the health effects of Dounreay were growing. In 1983 radioactive particles of spent fuel were found on adjacent beaches. How they got there has never been established; but investigations discovered a plume of radioactivity in the sea fanning out from the site. Late in 1985, even as the AEA was promoting a plan for a European Demonstration Reprocessing Plant for fast breeder fuel at Dounreay, the Thatcher Government cut funding for fast reactor development. Then, on 26 April 1986, came Chernobyl. The accident cast a pall over every form of nuclear activity. Public opposition erupted, even at Dounreay. Then yet another steam-generator failure shut down PFR for six months.

On 21 July 1988, minister Cecil Parkinson announced in the House of Commons that annual funding for fast breeders was to be cut from £105 million to £10 million, that funding for the PFR would cease after 1994 and for Dounreay reprocessing after 1997. It was the death knell for the U. K. fast breeder programme. After four decades of effort, and public expenditure of over £2400 million, it had proved to be a radioactive dead end.

Two decades after Parkinson’s announcement, the cleanup of Dounreay continues, as does the drain on public funds. The once all-powerful AEA, broken up and sold to private interests, is a shadow of its former self. But work at Dounreay will last for decades to come. Decommissioning the PFR, dealing with the now-notorious shaft, clearing up ponds and other facilities and decontaminating the site will last into the 2030s and beyond, at a cost as yet difficult to determine. Looming in the background is one further question. The collapse of the fast breeder program leaves the U. K. with an inventory of separated plutonium amounting to about 100 tonnes. What is to become of it? No one in Government is saying — probably because no one knows.

Endnotes

1. Margaret Gowing and Loma Arnold, Independence and Deterrence: Britain and Atomic Energy, 1945-52, 2 Vols. (London: Macmillan, 1974).

From the very beginning there were questions about how to remove heat produced in a fast-neutron reactor’s compact core. Sodium was chosen as the best coolant based on theoretical research and experiments.

A serious drawback of sodium is that it burns in water. A number of experiments at IPPE and experience gained with the BR-5, BN-350, BOR-60 and BN-600 suggested that this problem is not a major issue for fast-neutron-reactor safety. Even the 1973 sodium fire at the BN-350 did not affect reactor safety. Problems with steam — generator design were corrected step-by-step.

Fortunately, before the startup of construction of the BN-350, it was discovered that steel swelling under high neutron fluence was problematic. At the last moment, the fuel assembly design was modified to take into account the swelling and the planned burn-up of the fuel was limited (though subsequently increased on the basis of further experience). Irradiation tests on different types of steel were made in the BOR-60, BN-350 and BN-600 reactors for consideration in future projects.19

Mercury was initially considered as a coolant but is highly corrosive to most reactor materials. Although sodium-potassium alloy is a good coolant (with a low melting temperature of approximately 20 oC so that a heating system is not required for liquefaction), the alloy is more flammable then pure sodium.

Lead and bismuth and their alloys are more promising as fast-reactor coolants. Neutrons do not lose a significant amount of energy when they collide with the heavy nuclei of these elements. They are not flammable and do not react with water. At the same time, however, they are significantly more corrosive to steel than sodium with corrosion properties that are dependent on the oxygen content in the alloy. Research on lead-bismuth alloys was initiated in 1951.20 They are effective coolants for compact nuclear reactors, which is why they were used for submarines.21 During the past decade, the alloy was considered as a coolant for a new type of fast-neutron reactor, the BREST project. Rosatom22 has decided to build an experimental 75 MWt reactor with lead-bismuth coolant (SVBR-75/100) before developing a commercial prototype.23

Thus far, most of the fuel in the BN-350 and BN-600 reactors has been uranium dioxide. Some experience with mixed-oxide (MOX) uranium-plutonium fuel was acquired in the BOR-60 reactor and in a few experimental fuel assemblies in BN — 350 and BN-600. Limited experience in carbide and nitride fuel was gained with the BR-5/10 but not enough to deploy these fuels in a future fast-neutron reactor.

Recently, the director general of the Research Institute of Atomic Reactors, Alexander V. Bychkov, declared that most of the problems of vibro-packed fuel — fabrication technology have been solved and that it is ready for commercial implementation.24 However, full-scale experiments with closed fuel cycles have not been conducted.

Seven tons of BOR-60 fuel have been reprocessed, 4 tons of which were MOX and some of the separated plutonium was recycled. A number of questions are unresolved. How will a transition between bench scale and commercial scale technology influence the quality of the fuel pins and assemblies? If pyro-chemical processing is used, the degree of separation of the fission products will have to be determined.

Thomas B. Cochran, Harold A. Feiveson, and Frank von Hippel

Immediately after the bombing of Pearl Harbor on December 2, 1942, research on plutonium production for atomic weapons was consolidated at the University of Chicago under Nobel Laureate Arthur H. Compton. The "Metallurgical Laboratory" (later to become Argonne National Laboratory) was the code name given to Compton’s facility. It was here that a small group of scientists, led by Enrico Fermi, built the world’s first reactor, Chicago Pile-1 (CP-1), which achieved initial criticality on 2 December 1942. During the next two years, work on the development of plutonium production reactors shifted to Oak Ridge and then Hanford. By early 1944, Compton and the Chicago scientists began thinking about the role of the Metallurgical Laboratory after the war.1

On the morning of April 26, 1944, Enrico Fermi, Leo Szilard, Eugene Wigner, Alvin Weinberg and others gathered to discuss the possibilities for using nuclear fission to heat and light cities.2 The scarcity of fissile material was on everyone’s mind. It was unclear at that time whether there was sufficient uranium even for producing highly enriched uranium and plutonium for a significant number of nuclear weapons. Fermi and his colleagues at the Metallurgical Laboratory therefore cast around for ways to produce maximum power — or plutonium for weapons — with minimal resources.3 They recognized that some reactor configurations might permit the conversion of uranium-238 to fissile (chain-reacting) plutonium at a rate faster than the fissile uranium-235 was consumed, hence the term "breeder reactor."

Walter Zinn, one of the nation’s few reactor experts and a close colleague of Fermi, was soon recruited to the cause.4 By summer of 1944 he had begun a more detailed investigation of breeder reactor designs. By the end of 1945, he had abandoned the idea of breeding uranium-233 in thorium and confirmed the original plan of breeding plutonium-239 from uranium-238 using fast fission neutrons.5 In 1945 Enrico Fermi said, "The country which first develops a breeder reactor will have a great competitive advantage in atomic energy."6

The world’s first fast-neutron reactor was Clementine, a 25 kilowatt thermal (KWt), mercury-cooled experimental reactor built at Omega Site (TA-2) at Los Alamos.7 It was proposed and approved in 1945. High intensities of fission-spectrum neutrons were needed by the bomb designers. Also, operation of the reactor would supply information about fast reactors that would be relevant to their possible use for production of power and fissile materials.8

Construction began in August 1946, criticality was achieved in late-1946, and full power in March 1949. The fuel was plutonium metal with natural uranium slugs at each end of the steel-clad rods. The rods were installed in a steel cage through which the liquid-mercury coolant flowed, driven by an electromagnetic pump. The core was surrounded concentrically with a 15 cm thick natural uranium reflector, a 15 cm thick steel reflector and a 10 cm thick lead shield.9

Clementine was shut down in March 1950 due to a control rod malfunction. Operations resumed in September 1952. It operated only until 24 December 1952, however, when a fuel rod ruptured. The uranium slugs swelled, burst the cladding and released plutonium into the mercury coolant.10 The reactor was subsequently dismantled.

After Clementine, Los Alamos developed and briefly operated one additional fast reactor, LAMPRE-I. This sodium-cooled reactor was fueled with molten plutonium. It achieved initial criticality in early-1961 and operated successfully for several thousand hours until mid-1963. Designed to explore issues associated with using plutonium fuel in fast breeder reactors, it was originally intended to operate at 20 megawatt thermal (MWt). It became apparent, however, that knowledge was inadequate about the behavior of some of the core materials in a high-temperature, high-radiation environment.11 The design power therefore was reduced to 1 MWt, with the plan to follow LAMPRE-I by a 20 MWt LAMPRE-II. By mid-1963, LAMPRE-I had served its intended purpose and was shut down. Funding for the construction of LAMPRE-II never materialized.12

Admiral Hyman G. Rickover briefly experimented with fast-neutron reactors for naval submarine propulsion. This effort began with General Electric’s development and operation for the Navy of the land-based S1G prototype at the Knolls Atomic Power Laboratory in West Milton, New York. The S1G, which was HEU-fueled, operated from the spring of 1955 until it was shut down in 1957 after Admiral Rickover abandoned fast reactors for naval propulsion. During its brief operating history, the sodium-cooled S1G experienced trouble with leaks in its

і 3

steam generators.13

The S1G prototype was followed by the deployment of the S2G fast reactor in the nuclear submarine, USS Seawolf (SSN 575). According to Atomic Energy Commission (AEC) historians, Hewlett and Duncan, in their history of the U. S. nuclear navy from 1946 to 1962:

Although makeshift repairs permitted the Seawolf to complete her initial sea trials on reduced power in February 1957, Rickover had already decided to abandon the sodium-cooled reactor. Early in November 1956, he informed the Commission that he would take steps toward replacing the reactor in the Seawolf with a water-cooled plant similar to that in the Nautilus. The leaks in the Seawolf steam plant were an important factor in the decision but even more persuasive were the inherent limitations in sodium-cooled systems. In Rickover’s words they were ‘expensive to build, complex to operate, susceptible to prolong shutdown as a result of even minor malfunctions, and difficult and time-consuming to repair.’14

Consolidation of breeder reactor research at Argonne National Laboratory

In 1946, the newly formed AEC took control of the nation’s nuclear research facilities and tapped Zinn to head the Chicago laboratory, which by then had been reorganized and renamed Argonne National Laboratory (ANL). The next year, the AEC Commissioners decided to consolidate the entire AEC reactor program at ANL.15 The Commission needed reactors not only to produce plutonium for weapons but also for the production of radioisotopes and for general research. There was also widespread public interest in using reactors to generate electric power.16

In drafting his section of the General Advisory Committee report, Zinn stressed power reactors. Here (as had been the case since 1944) a fact of supreme importance was the shortage of fissionable material. Existing stocks of uranium ore seemed scarcely large enough to sustain production of a modest number of weapons, to say nothing of providing fuel for power plants. Zinn believed the only hope for power reactors lay in those which would breed more fissile material than they consumed.17

Zinn convinced the AEC to give the breeder project a high priority and insisted on directing the effort himself. Fermi promoted it by giving lectures extolling the goal of extracting almost 100 percent of the fission energy from natural uranium.18

Experimental Breeder Reactor-I

On November 19, 1947, the AEC authorized ANL to design and build a liquid- metal-cooled, fast-neutron reactor, the second fast reactor in the United States, Experimental Breeder Reactor-I (EBR-I), alternately known as "Chicago Pile 4" and "Zinn’s Infernal Pile."

The EBR-I team decided to cool the reactor core with a sodium-potassium (NaK) alloy. Since they knew little about the effect of this liquid-metal coolant on materials and worried that the control rods might stick or corrode, they decided to cool them with air, which introduced the complexity of designing two completely separate cooling systems. This was especially hard because the sodium-potassium metal would burn in both water and air. Therefore, there could be no fluid leakage.19

From the beginning of the Manhattan Project, questions had been raised about the public safety concerns associated with building reactors in the Chicago area. By summer 1948, Zinn was convinced the project needed to be built at a remote site and asked the AEC to find one.20 The Commissioners chose a site near Arco, Idaho, that had been a proving ground for navy ordnance. It came to be known as the National Reactor Testing Station, now part of the Idaho National Laboratory (INL) and soon housed other ANL reactor projects as well as other government reactors.21

EBR-I was the first fast-neutron reactor designed to both breed plutonium and to produce electric power. The 1.2 MWt (0.2 megawatt electric)22 sodium-cooled reactor went critical on December 20, 1951, and lit four 200-watt light bulbs, thereby becoming the world’s first electricity-generating nuclear power plant. See figure 7.1. EBR-I was fueled with weapon-grade (94 percent-enriched) uranium. On June 4, 1953, the AEC announced that EBR-I had become the world’s first reactor to demonstrate the breeding of plutonium from uranium.

Unfortunately the reactor was designed with a prompt positive power coefficient of reactivity (increases in power had a positive feedback). On November 29, 1955, during an experiment to obtain information about this instability, the reactor had a partial (40-50 percent) core meltdown. The damaged core was removed and the reactor was repaired and operated until it shut down on December 30, 1963.

The accident at EBR-I focused attention on safety issues associated with liquid — sodium fast-neutron reactors and especially the possibility of an explosive criticality due to the partial melting and collapse of the core. This possibility was first studied by Bethe and Tait.23 By 1983, the effective end to the U. S. fast reactor commercialization program, U. S. analysts had concluded that the Bethe — Tait analysis was overly conservative regarding the magnitude of the potential energy release in a fast-reactor accident, but that there were no "universally accepted estimates of upper limits on consequences of hypothetical fast-reactor accidents."24

The one kilowatt (KW) ANL Fast Source Reactor was also built at the National Reactor Testing Station to produce neutrons for the fast reactor development program. Reactor startup occurred on October 29, 1959 and the reactor was operational until sometime in the late-1970s, when it was moved to a new location on the Idaho site.

Walt Patterson

Margaret Gowing’s masterly official history of postwar nuclear activities in Britain, Independence and Deterrence, describes disputes among the nuclear physicists at the Atomic Energy Research Establishment at Harwell:1

The only point on which there was general agreement… was on the long term future on the ultimate and overriding importance of breeder reactors, which would produce more secondary fuel than the primary fuel they consumed.

The reason for this island of unanimity amid the prevailing conflict of views was straightforward. In the late 1940s and early 1950s uranium was scarce and expensive; moreover its supply was politically acutely sensitive, because of the weapons implications.

In consequence, as Harwell director Sir John Cockcroft explained:

… we have to develop a new type of atomic pile (reactor) known as the ‘breeder pile’ because it breeds secondary fuel (plutonium) as fast or faster than it burns the primary fuel uranium-235 ….These piles present difficult technical problems, and may take a considerable time to develop into reliable power units. Their operation also involve difficult chemical engineering operations in the separation of the secondary fuel from the primary fuel.

By 1953, nuclear engineers at Risley, after working for some two years with their Harwell colleagues on the design of a fullscale fast breeder power station, concluded:

Edited, abridged and updated from Going Critical: An Unofficial History of British Nuclear Power, Walter C. Patterson, Paladin, 1985.

At first sight this fast reactor scheme appears unrealistic. On closer examination it appears fantastic. It might well be argued that it could never become a serious engineering proposition.

Nevertheless, in March 1955, construction work started on an experimental fast breeder power station at the new Atomic Energy Authority’s (AEA) Dounreay Experimental Reactor Establishment, on the north coast of Scotland. This remote location was chosen precisely for its remoteness, because of major questions about the possible behaviour and misbehaviour of a reactor whose core contained an unprecedented concentration of fissile material.

By the third AEA annual report, in mid-1957, the Dounreay Fast Reactor (DFR) was "expected to start operation in 1958". From 8 October 1957, however, the AEA was preoccupied with the aftermath of the Windscale fire, in which one of its graphite-moderated plutonium production reactors had burned and dispersed a large amount of radioactivity. The DFR did not actually go critical until November 1959. The 1960 annual report remarked, "A prototype power producing reactor may be built for operation about the year 1967, the development of which will enable a commercial power station to be specified."

The design output of the DFR was to be 60 megawatts of heat (MWt), or 14 megawatts of electricity (MWe). Successive AEA annual reports stressed that the DFR was "experimental," "intended to develop the technology of fast reactors generally." It fulfilled this role admirably, in that it succumbed to a fascinating variety of novel engineering difficulties, particularly those arising from the use of molten-sodium-potassium alloy as the cooling fluid. By mid-1961 its highest output had been 1.5 MWt. By mid-December the reactor had been run up to 11 MWt, at which point it was shut down to have its fuel core replaced with one of improved design. While thus busy with the DFR, the AEA in 1961-62 was also completing a design study for a 500 megawatt (MW) fast breeder power station. The next step in the program would be to try out the concepts on an intermediate scale, on what would be known as the Prototype Fast Reactor (PFR). The DFR reached an output of 30 MWt, half its intended design output, on 7 August 1962, and remained at this level for the rest of the year. In October it supplied electricity to the national grid for the first time.

The Select Committee on Nationalized Industries, in its May 1963 report on the electricity supply industry, noted that "the development by the Atomic Energy Authority of a fast breeder reactor at Dounreay… remains a long term project. The Authority hopes that a prototype will be operating by 1969 or 1970; and the first civil station would not be working before 1975." The 1963-64 annual report of the AEA declared that "Consortia design engineers are engaged on a design study of a 1000 MWe power producing fast reactor." At the time, the largest thermal reactors contemplated for construction were 660 MWe. In July 1963 the DFR at last attained its full design output of 60 MWt, or 14 MWe, and operated at this level for most of the ensuing year.

In 1964-65, the AEA completed two design studies for fast breeders. The first was for the proposed PFR. It was to have an output of 600 MWt or 250 MWe; but it was designed to use components suitable for a full scale commercial fast breeder power station. By August 1965 AEA staff were already preparing detailed designs and specifications for major plant and civil engineering contracts for PFR. This was well before the official go-ahead for PFR, which did not come until 9 February 1966.